Elastic yarn and method of making the same



\ Nowfl, 1936. I F. D. CHITTENDEN ET AL I 2,

ELASTIC YARN AND METHOD OF MAKING THE SAME Filed April 1, 1936 INVENTORSPatented Nova 17, 1936 UNITEDSTATES PATENT oFFI ELASTIC YARN AND METHODOF MAKING THE SADIE Application April 1, 1936, Serial No. 22,100

3 Claims.

This invention relates to a'balanced, singlecover elastic yarn and to anovel method of making the same.

The Boutwell H. Foster Patent No. 2,024,156 discloses and claims abalanced, single-cover elastic yarn formed by supplying a pre-twis'tedrubber core and a drafted roving of fibres to spinning mechanism andspinning. the fibres about the twisted core as a cover. The eifect ofthe spinning operation is to remove part but not all of the twist fromthe core as the cover is spun thereupon so as to produce an elastic yarnin which the twist ofthe core in one direction balances the helicalwindings of the cover in the opposite direction. A second Foster PatentNo. 2,024,155 discloses a balanced, single-cover elastic yarn describedas formed by supplying a pretwisted rubber core to winding mechanismwhich winds 9. covering yarn about the core in the reverse direction tothe twist of the core.

In accordance with the disclosure of these two patents, the rubber coreis pre-twisted, that is, the core is twisted in one direction before thecover is wrapped helically thereupon in the opposite direction. Inaccordance with the present invention the rubber core is not pre-twistedbut a covering yarn is wound helically about a straight untwisted rubbercore. This produces an unbalanced elastic yarn, but the unbalancedcondition is corrected by twisting the elastic yarn in a direction todecrease the helical coils upon the core and impart a counter-balancingtwist to the core. The correcting twist imparted to the unbalancedelastic yarn should be just enough to balance the yarn so that it willhang free and straight in the skein without kinking. It is found inpractice that one twist imparted to the core as herein contemplated willbalance a number of oppositely wound coils of the cover. Therefore, theoperation of balancing the yarn as herein contemplated does not removeenough coils from the cover to appreciably disturb the coveringproperties of the helically wound cover as first applied to the core.

One important property of the elastic yarn of the present inventionresults from the fact that the rubber core has relatively few turns perinch and is therefore under less internal stress than a highly twistedcore. It will therefore last longer and will retain its elasticproperties better than a highly twisted core. Another important propertyof this elastic yarn results from the fact that the low twists of thecore and high number of helical coils of the cover produces an elasticyarn that may have an elongation of three hundred from a spool l l.

. may unwind from this spool is controlled by causpercent (300%) ormore. A further feature of the invention resides in a well covered andeasily manufactured elastic yarn that retains its balanced conditionwell.

The elastic yarn of the present invention and method of making the samewill be more fully understood from the following'description andaccompanying drawing wherein:

Figure 1 is a side elevation of mechanism for applying a single cover toan elastic core;

Figure 2 is a side elevation of 'mechanismfor balancing an unbalancedelastic yarn;

Figure 3 is a side elevation of a modified form of mechanism whereby theoperations of Figs. 1 and 2 may be performed continuously;

Figure 4 is an enlarged side elevation of a single-cover elastic yarnwhich may ,be produced upon the mechanism of Fig. 1; and

Figure 5 is a similar view of the elastic yarn of Fig. 4 after it hasbeen balanced by being treated upon the mechanism of Fig. 2.

In carrying out the present invention the elastic core l0 may be made byany suitable or known method of producing a strong durable rubberthread, but the core shown is round in crosssection and is preferablyformed of an extruded aqueous dispersion of rubber, in accordance withthe disclosure of the Hopkinson and Gibbons Patent No. 1,545,257 grantedJuly 7, 1925.

Various types of winding mechanism may be employed for winding a coverhelically about the rubber core l0 and in accordance with the disclosureof Fig. 1 the rubber core I0 is supplied The rate at which the core ingthe supply of thread wound upon the spool to rest upon a roller it whichmay be driven at a constant speed. The rubber core Ill is shown asextending upwardly through a hollow spindle l3 which is rotatablysupported in the bracket orframe It and the spindle may be driven by thebelt ill or by other means as desired.

The covering yarn 16 may be supplied by a package ll wound upon asupporting tube it, and difierent forms of mechanism may be employed fordelivering the yarn 16 from the pack age I? to the core-coveringposition. This is accomplished in the construction shown by placing thetube l8 upon an adapter 19 of well known construction and having thehead 20. The adapter is placed upon the spindle l3 to be rotatedtherewith. Upon the head 20 in the present construction is rotatablymounted a disc flyer 2| which may have a thread-guiding notch or openingat its outer edge. This disc serves to hold that one twist imparted tothe core I0 will serve the yarn 16 out of engagement with the head 20 asit is delivered to the core and the disc turns freely upon the head tocontrol the tension of the yarn.

The rubber core 10 is maintained under any desired tension during thecovering operation, in the construction shown, by passing the covered orelastic yarn 22 between the cooperating rollers 23 and 24 which aredriven by the roller 25 at a sufficiently higher surface speed than theroller I2 to stretch the core I0 the desired amount. The covered yarn 22passes from the roller 24 through traversing mechanism 26 which guidesit to the take-up spool 21, that is driven by the roller 28. v

The rubber core 10 wound upon the spool H is in a straight; that is,untwisted condition, and it will therefore be seen that the effect ofwindingthe coveringya'rn 16 upon the stretched untwisted core II will beto produce an unbalanced elastic yarn, such as shown in Fig. 4.

In order to balance the yarn 22, the'spool 21 with this yarn woundthereupon may be transferred from the position in which itis shown inFig. 1 to the spindle 29 of Fig. 2 where it is designated by 213:. Thespindle 29 may be driven at the proper speed by any suitable means suchas the electric motor 290:. As the unbalanced elastic yarn 22 is unwoundfrom the spool 213:

Hi. It will, therefore, be seen that in twisting the elastic yarn 22 ofFig. 4 to balance the same it is necessary to remove only about 1/10 to1/20 of the coils shown in Fig. 4 while twisting the core l0sufficiently to produce the balanced elas- =tic yarn of Fig. 5, andsince the covering yarn i6 is applied while the core is stretched and iswound tight upon the core to hold it stretched, the expansion of thiscore laterally during the balancing operation will serve to take up allslack which may result from slightly untwisting the cover.-

Elastic yarn constructed in accordance with the present invention due tothe smallamount of twist imparted to the core maintains its balancedcondition well and is well adapted for use where a low-tensionlong-stretch yarn is desired, for the core may be stretched less than10% in the relaxed or normal elastic yarn of Fig. 5 and this yarn may becapable of stretching over 300% from the normal condition withoutbreaking either the core or cover.

The properties of thepresent yarn will be further understood from thefollowing table in which four sample yarns are analyzed. It is to beunderstood, however, that the specifications of this table are not givenwith any intention of limiting the invention more than is required bythe scope of the prior art.

Analyses of single-cover elastzc yarns Sample No. 1 N0. 2 No. 3 I No. 4

Core 75's round 37's round 44's round 75s round. Cover 1-36/1 cotton3-50/2 cotton 3-80/1 cotton 1-24/1 cotton. Wraps of covering per inch ofelastic yam 8O 40 75 83 Twist in core per inch of elastic yarn 9 5 12 18Length of bare core per yd.

elastic yarn 34 27" 21" 30 Percent core- 51 46 66 36 Percent cover 49 5444 64 Yards in one pound of elastic yarn relaxed 3400 900 2000 2500Elongation or stretch of the elastic yarn 330% 250% 250% 265% Note-Thesize of the rubber core is indicated by the number that may be laid sideby side to form one inch.

of Fig. 2 it passes upwardly about the head of the spool 21m to a guideeye 30 and then upwardly to the yarn tensioning or take-up pulley 3|about which it is looped. The yarn upon leaving this take-up pulleypasses through traversing mechanism 32 and may then be wound upon theskein receiving drum 33 driven by the friction roll 34. The take-uppulley 31 is preferably driven at a surface speed several times fasterthan the surface speed of the drum .33 and the slippage of the yarnabout this pulley will compensate for variations in the stretch of theelastic yarn being withdrawn from the supply spool 21a: so that the yarnwill be delivered to the drum 33 underpractically constant tension.Thethread guides 35 and 36 are preferably provided to guide the elasticyarn 22 to and from the take-up pulley 3|.

The rotation of the spindle 29 should be in a direction to remove a fewspiral wraps per inch from the elastic yarn 22 and at the same timeimpart a few reverse twists to the core III, as willbe apparent fromFig. 5. As above stated, it is found necessary to impart only arelatively few twists to the elastic yarn of Fig. 4 in order to. twistthe core as shown in Fig. 5 sufiiciently to balance the large number ofhelical coils of the covering yarn 16. For example, it .is found tobalance from 5 to 10 helical coils of the yarn In most cases it will bedesirable to carry out the operation of covering the elastic core uponone machine (such as shown in Fig. 1) and of counterbalancing theunbalanced elastic yarn on a separate machine, such as shown in Fig. 2,because the operation of covering the core shown in Fig. 1 is muchslower than that of correcting the balance of the yarn as shown in Fig.2. However, if desired, these two operations may be carried outcontinuously by employing mechanism such as shown in Fig. 3 wherein themechanism for covering the elastic core may be identical with that shownin Fig. 1 and after the elastic core is covered it may pass upwardlybetween the cooperating of pinch rolls 31 and 38 which are driven at thedesired speed. This yarn may then be led downwardly from the roll 38 tothe guide eye 39 upon the axis of spinning mechanisms, and from thisguide eye to a traveler 40 mounted'upon the usual ring 4| of the ringand traveler type of spinning mechanism, whereupon the yarn may be woundupon the spool or package '42 mounted upon the spinning spindle whichspindle may be driven by a belt 44.

Having thus described our invention what we claim and desire to protectby Letters Patent is:

1. The method of making a balanced, singlecover elastic yarn whichconsists in wrapping yarn helically about a straight rubber core whilethe latter is stretched to produce an unbalanced elastic yarn, and thentwisting the unbalanced yarn in a direction to impart a sufllcientreverse twist to the core to balance the elastic yarn.

2. The method of making a balanced, singlecover elastic yam whichconsists in wrapping yarn helically about a straight rubber core whilethe latter is under tension to produce an unbalancedelastic yarn, andthen balancing this elastic yam by twisting the unbalanced yarn in adirection to decrease the coils of the cover by not more than 20% andimpart a reverse twist to the core.

3. The method or making a balanced, singlecover elastic yarn whichconsists in wrapping a textile filament helically about a straightrubber core to produce an unbalanced elastic yarn. and

then balancing this elastic yarn by imparting a relatively few twists tothe elastic yarn in a direction to decrease the helical coils upon thecore and impart a reverse twist to the core.

FAYE'I'I'E n. CHI'I'I'ENDENJ 10 m J. RUPPRmHT.

